Memory device with programmable parameter controller

ABSTRACT

A memory device having the capability of controlling a characteristic parameter including a register controller including a nonvolatile memory unit for storing data and a parameter controller for outputting a signal corresponding to a predetermined input signal. The parameter controller controls one or more characteristic parameters of the memory unit, including input voltage sensitivity, output signal delay and output signal voltage, according to a signal outputted from the register controller.

CORRESPONDING RELATED APPLICATION

This application is a divisional of U.S. application Ser. No. 10/626,775filed Jul. 25, 2003, now U.S. Pat. No. 7,120,041 which claims priorityto Korean Patent Application No. 10-2002-81102 filed Dec. 18, 2002,which are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to memory devices, and more particularlyto a memory device including a parameter controlling device forregulating characteristic parameters of the memory device such as avoltage level of an input signal, a timing characteristic, and a voltagelevel of an output signal, by using a programmable method.

2. Description of the Prior Art

During the development of a memory device, signal performancecharacteristics, which are characteristic parameters of a circuit suchas a voltage level of a signal inputted in a chip, a timingcharacteristic (e.g., signal delay), and a voltage level of a signaloutputted from the chip, are necessarily re-adjusted within a simulationerror range.

The production of the conventional memory device is commenced only afteramending the masks to apply or achieve the adjusted parameters. As aresult, the production of a device using a new mask requires extra timeand cost to establish the device's characteristic parameters or signalperformance characteristics.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to easily regulatecharacteristic parameters without physically amending the masks by usingprogrammable registers.

There is provided a memory device including a parameter controllingdevice, comprising: a register controller including a nonvolatile memoryunit for storing data in the nonvolatile memory unit; and a parametercontroller for outputting a signal having characteristics depending on asignal outputted from the register controller.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a structure of a memory deviceaccording to an embodiment of the present invention.

FIG. 2 is a block diagram showing a main bitline pull-up controller, acell array block and a column selection controller of FIG. 1.

FIG. 3 is a detailed structural diagram showing the main bitline pull-upcontroller of FIG. 1.

FIG. 4 is a detailed structural diagram showing a main bitline loadcontroller of FIG. 2.

FIG. 5 is a detailed structural diagram showing the column selectioncontroller of FIG. 1.

FIG. 6 is a detailed structural diagram showing a sub-cell block of FIG.2.

FIG. 7 is a structural diagram showing a first register controller andan address input buffer unit of FIG. 1.

FIGS. 8 a through 8 c are detailed structural diagrams showing anaddress input buffer of FIG. 7.

FIG. 9 is a structural diagram showing a fourth register controller anda timing controller of FIG. 1.

FIGS. 10 a through 10 b are structural diagrams of the timing controllerof FIG. 9.

FIG. 11 is a structural diagram showing a fifth register controller anda voltage level controller of FIG. 1.

FIGS. 12 a through 12 c are structural diagrams showing the voltagelevel controller of FIG. 11.

FIG. 13 is a structural diagram showing a register command processorincluded in a memory device according to the present invention.

FIGS. 14 a and 14 b are timing diagrams showing a program mode decodingoperation according to the present invention.

FIG. 15 is a structural diagram showing a D flip-flop of FIG. 13.

FIG. 16 is a structural diagram showing a register included in a memorydevice according to the present invention.

FIGS. 17 a through 17 b are timing diagrams illustrating write/readoperation respectively.

FIG. 18 is a circuit diagram showing the register of FIG. 16 foroutputting a register control signal of FIG. 16.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will be described in more detail with reference tothe accompanied drawings.

FIG. 1 is a block diagram showing a structure of a ferroelectric memorydevice including a parameter controlling device according to anembodiment of the present invention. The memory device in thisembodiment comprises a cell array block 100, a main bitline pull-upcontroller 11, a column selection controller 12, a sense amplifier array30, a data I/O buffer 50, a switch controller 40, a first registercontroller 510, a second register controller 520, a third registercontroller 530, a fourth register controller 540 and a fifth registercontroller 550. The main bitline pull-up controller 11 pulls up a mainbitline included in the cell array block 100 to a positive voltage. Thecolumn selection controller 12 connects the main bitline to a data bus21. The sense amplifier array 30 is connected to the data bus 21. Thedata I/O buffer 50 exchanges data externally. The switch controller 40is connected between the sense amplifier array 30 and the data I/Obuffer 50. The first register controller 510 controls an address inputbuffer unit 210. The second register controller 520 controls a controlinput buffer unit 220. The third register controller 530 controls a datainput buffer unit 230. The fourth register controller 540 controls atiming controller 300. The fifth register controller 550 controls avoltage level controller 400.

FIG. 2 is a block diagram showing a main bitline pull-up controller 11,a cell array block 100 and a column selection controller 12 of FIG. 1.The cell array block 100 includes a plurality of main bitline loadcontrollers 13 and a plurality of sub cell blocks 110. There may be oneor more main bitline load controllers 13.

FIG. 3 is a detailed structural diagram showing the main bitline pull-upcontroller 11 of FIG. 1. The main bitline pull-up controller 11comprises a PMOS transistor having a gate to receive a control signalMBPUC, a source connected to a power source VPP(VCC) and a drainconnected to a main bitline MBL.

The main bitline pull-up controller 11 pulls up the main bitline MBL ina precharge operation.

FIG. 4 is a detailed structural diagram showing the main bitline loadcontroller 13 of FIG. 2. The main bitline load controller 13 comprises aPMOS transistor having a gate to receive a control signal MBLC, a sourceconnected to the power source VPP(VCC) and a drain connected to the mainbitline MBL.

The main bitline load controller 13, working as a resistive deviceconnected between the power source VPP(VCC) and the main bitline MBL,determines a voltage of the main bitline MBL according to the amount ofcurrent flowing through the main bitline load controller 13 during adata sensing operation.

One or more main bitline load controllers 13 are connected to one mainbitline MBL (see FIG. 1). When two or more main bitline load controllers13 are connected, the same number of sub cell blocks 110 are assigned toa main bitline load controller 13, and the main bitline controllers 13may be evenly (approximately) placed apart from each other.

FIG. 5 is a detailed structural diagram showing the column selectioncontroller 12 of FIG. 1. The column selection controller 12 is a switchfor connecting the main bitline MBL and the data bus that is turnedon/off by control signals CSN and CSP.

FIG. 6 is a detailed structural diagram showing the sub cell block 110of FIG. 2. One sub cell block comprises a sub bitline SBL, and NMOStransistors N1, N2, N3, N4 and N5. The sub bitline SBL is connected incommon to a plurality of unit cells connected to a number (n) ofwordlines WL<n> and a number (n) of platelines PL<n>, respectively. TheNMOS transistor N1 for regulating a current has a gate connected to afirst terminal of the sub bitline SBL, and a drain connected to a mainbitline MBL. The NMOS transistor N2 has a gate connected to a controlsignal MBSW, a drain connected to a source of the NMOS transistor N1,and a source connected to ground. The NMOS transistor N3 has a gateconnected to a control signal SBPD, a drain connected to a secondterminal of the sub bitline SBL, and a source connected to ground. TheNMOS transistor N4 has a gate connected to a control signal SBSW2, asource connected to a second terminal of the sub bitline SBL, and adrain connected to a control signal SBPU. The NMOS transistor N5 has agate connected to a control signal SBSW1, a drain connected to the mainbitline MBL, and a source connected to the second terminal of the subbitline SBL.

When a unit cell is accessed, the sub bitline SBL connected to thecorresponding unit cell is connected to the main bitline MBL. The subbitline SBL is connected to the main bitline MBL via the NMOS transistorN5. As a result, the amount of load for driving a bitline decreases tothat corresponding to one sub bitline.

If a SBPD signal is activated, a potential of the sub bitline SBL isregulated to ground level. The SBPU signal regulates a power voltage tobe supplied to the sub bitline SBL. The control signal SBSW1 controls asignal flow between the main bitline MBL and the sub bitline SBL. Thecontrol signal SBSW2 controls a signal flow between the signal SBPU andthe sub bitline SBL.

The sub bitline SBL connected to the gate to the NMOS transistor N1regulates a sensing voltage of the main bitline MBL. The main bitlineMBL is connected to the power source VPP(VCC) via the main bitline loadcontroller 13 (illustrated in FIGS. 2 and 4). If a control signal MBSWis “high”, a current flows from the power source VPP(VCC) via the mainbitline MBL and the NMOS transistors N1 and N2 to the ground. Here, theamount of the current is determined by a voltage of the sub bitline SBLprovided to the gate of the NMOS transistor N1. If the datum stored inthe cell is “1”, the amount of the current increases, and the voltage ofthe main bitline MBL decreases. If the datum stored in the cell is “0”,the amount of the current decreases, and the voltage of the main bitlineMBL increases. Thus, the cell datum can be detected by comparing thevoltage of the main bitline MBL with a reference voltage. The detectionof the cell datum is performed in the sense amplifier array 30.

FIG. 7 is a structural diagram showing the address input buffer unit 210and the first register controller 510 of FIG. 1.

The address input buffer unit 210 comprises a plurality of address inputbuffers (address input buffer_0 . . . address input buffer_n), each ofwhich is connected to a plurality of address pads A0_Pad, A1_Pad, . . .An_Pad. The first register controller 510 comprises a register array 511including a plurality of registers REG_0, . . . REG_m, and a registercommand processor 512 for controlling the registers. Each address inputbuffer receives signals RE_0, RE_1, . . . RE_m outputted from theregister array 511. The structures of the register command processor 512and each register REG_0, REG_1, . . . REG_m will be explained in detailin FIG. 13.

FIG. 8 a is a first example embodiment of each address input bufferincluded in the address input buffer 210. Each address input buffercomprises a current controller 211, a PMOS transistor CP, a NMOStransistor CN, and a BUFFER 212. The current controller 211 comprises aplurality of PMOS transistors P₀, . . . P_(m) having gates to receiveoutput signals RE_0, . . . RE_m from the registers of the register array511 and sources connected to power source VCC. The PMOS transistor CPhas a source connected to drains of the PMOS transistors P₀, . . .P_(m). The NMOS transistor CN has a drain connected to a drain of thePMOS transistor CP. The BUFFER 212 is connected to the drain of the NMOStransistor CN. An address input pad Input_Pad is connected to a gate ofthe PMOS transistor CP and the NMOS transistor CN.

The amount of a current provided to a source of the PMOS transistor CPvaries according to the number of turned-on transistors among the PMOStransistors P₀, . . . P_(m). As a result, a detection level of a signalprovided to the address input pad Input_Pad can be adjusted. Thus, thisembodiment comprises a detection level characteristic parametercontroller that controls the input signal sensitivity by activating anumber of registers in register array 511 via register command processor512.

FIG. 8 b is a second example embodiment of each address input bufferincluded in the address input buffer 210. In the second exampleembodiment, a capability for controlling activation in response to thechip enable signal CEB is added to the first example embodiment of FIG.8 a. A PMOS transistor CP₀ corresponds to the PMOS transistor CP of FIG.8 a, and a NMOS transistor CN₀ corresponds to the NMOS transistor CN ofFIG. 8 a. In the second example embodiment, a PMOS transistor CP₁ and aNMOS transistor CN₁ are added. The PMOS transistor CP₁ is connectedbetween the PMOS transistor CP₀ and the NMOS transistor CN₀. The NMOStransistor CN₁ is connected between a drain of the NMOS transistor CN₀and ground. The chip enable signal CEB is connected to a gate of thePMOS transistor CP₁ and the NMOS transistor CN₁. Thus, this embodimentcomprises a detection level characteristic parameter controller thatcontrols the input signal sensitivity by activating a number ofregisters in the register array 511 via the register command processor512.

If the chip enable signal CEB is activated to “high”, the NMOStransistor CN₁ is turned on. As a result, a “low” level signal isprovided to the BUFFER 212 regardless of a signal of the address inputpad Input_Pad. If the chip enable signal CEB is activated to “low”, thePMOS transistor CP₁ is turned on, and the rest of the circuit operationis similar to that described for the example embodiment of FIG. 8 a.Similarly, this embodiment comprises a detection level characteristicparameter controller that controls the input signal sensitivity byactivating a number of registers in the register array 511 via theregister command processor 512.

FIG. 8 c is a third example embodiment of each address input bufferincluded in the address input buffer 210. The current controller 211 ofthe third example comprises a plurality of NMOS transistors N₀, . . .N_(m). NMOS transistors N₀, . . . N_(m)has gates connected to outputsignals RE_0, . . . RE_m of registers, and sources connected to a powersource VSS.

In this example embodiment, address input pad Input_Pad is inputted to agate of the PMOS transistor CP₀ and to a gate of the NMOS transistorCN₀. The chip enable signal CEB is inputted to a gate of the PMOStransistor CP₁ and to a gate of the NMOS transistor CN₁.

The PMOS transistor CP₀ has a source connected to the power source VCC.The NMOS transistor CN₀ has a source connected to drains of the NMOStransistor N₀, . . . N_(m). The PMOS transistor CP₁ is connected inparallel to the PMOS transistor CP₀. The NMOS transistor CN₁ has asource connected to a drain of the NMOS transistor CN₀, and a drainconnected to a drain of the PMOS transistor CP₁. The BUFFER 212 isconnected to a drain of the PMOS transistor CP₀. The detailedexplanation on the operation of the third example embodiment is omittedbecause it is similar to that of the second example embodiment of FIG. 8b. Similarly, this embodiment comprises a detection level characteristicparameter controller that controls the input signal sensitivity byactivating a number of registers in the register array 511 via theregister command processor 512.

Explanations of structures of the control input buffer unit 220 and thesecond register controller 520, and structures of the data input bufferunit 230 and the third register controller 530 of FIG. 1 are omittedbecause these structures are similar to those of the address inputbuffer unit 210 of FIG. 7 and the first register controller 510 of FIGS.8 a through 8 c.

FIG. 9 is a structural diagram showing the timing controller 300 and thefourth register controller 540 of FIG. 1, which includes register array541 and register command processor 542. The detailed explanation on thefourth register controller 540 is omitted because it has the samestructure as the first register controller 510.

FIG. 10 a shows a first example embodiment of the timing controller 300.The timing controller 300 comprises a current controller 310, a PMOStransistor CP, a NMOS transistor CN and a delay capacitor 320. Thecurrent controller 310 comprises a plurality of PMOS transistors P₀, . .. P_(m) having gates to receive outputs RE_0, . . . RE_m and sourcesconnected to the power source VCC. The PMOS transistor CP has a sourceconnected to drains of the PMOS transistors P₀, . . . , P_(m). The NMOStransistor CN has a drain connected to a drain of the PMOS transistorCP. The delay capacitor 320 is connected between the source of the PMOStransistor CP and ground. An input signal Delay_In provided to a gate ofthe PMOS transistor CP and the NMOS transistor CN is delayed for apredetermined time and outputted at the drain of the PMOS transistor CPwith its level inverted.

The delay time is regulated by the current controller 310 and the delaycapacitor 320. Since the amount of a current provided to the source ofthe PMOS transistor CP varies according to the number of turned-ontransistors among PMOS transistors P₀, . . . P_(m) included in thecurrent controller 310, the resistance between the power source VCC andthe source of the PMOS transistor CP can be regulated. As a result, anRC delay time is regulated with the delay capacitor 320. Thus, thisembodiment comprises an RC delay time characteristic parametercontroller that controls the output signal delay by activating a numberof registers in the register array 541 via the register commandprocessor 542.

FIG. 10 b shows a second example embodiment of the timing controller300. Unlike FIG. 10 a, the delay capacitor 320 is connected betweenground and the drain of the NMOS transistor CN. The operationalprinciple is the same as that of FIG. 10 a described above. Similarly,this embodiment comprises an RC delay time characteristic parametercontroller that controls the output signal delay by activating a numberof registers in the register array 541 via the register commandprocessor 542.

FIG. 11 is a structural diagram showing the voltage level controller 400and the fifth register controller 550 of FIG. 1, which includes registerarray 551 and register command processor 552. The detailed explanationon the fifth register controller 550 is omitted because it works thesame as the first register controller 510 does.

FIG. 12 a shows a first example embodiment of the voltage levelcontroller 400. The voltage level controller 400 comprises a currentcontroller 410, a PMOS transistor CP, a NMOS transistor CN and a NMOStransistor 420. The current controller 410 comprises a plurality of PMOStransistors P₀, . . . P_(m) having gates to receive outputs RE_0, . . .RE_m and sources connected to the power source VCC. The PMOS transistorCP has a source connected to drains of the PMOS transistors P₀, . . .P_(m). The NMOS transistor CN has a drain connected to a drain of thePMOS transistor CP. The NMOS transistor 420 has a gate connected to thepower source VCC, a source connected to ground, and a drain connected toa source of the NMOS transistor CN.

A control signal Control_In is inputted to a gate of the PMOS transistorCP and the NMOS transistor CN. A voltage Voltage_Level is outputted fromthe drain of the PMOS transistor CP.

The amount of current flowing in the source of the PMOS transistor CPvaries according to the number of turned-on transistors among the PMOStransistors P₀, . . . P_(m)included in the current controller 410. As aresult, the value of the outputted voltage Voltage_Level variesaccording to the amount of the current. Thus, this embodiment comprisesan output voltage characteristic parameter controller that controls theoutput signal voltage by activating a number of registers in theregister array 551 via a register command processor 552.

FIG. 12 b shows a second example embodiment of the voltage levelcontroller 400. In the second example embodiment, the NMOS transistor CNof FIG. 12 a is not used. The drain of the NMOS transistor 420 isconnected to the drain of the PMOS transistor CP. The voltageVoltage_Level is outputted from the drain of the PMOS transistor CP. Theexplanation of the other operation is omitted because it is the same asthat of the first example embodiment. Similarly, this embodimentcomprises an output voltage characteristic parameter controller thatcontrols the output signal voltage by activating a number of registersin the register array 551 via a register command processor 552.

FIG. 12 c shows a third example embodiment of the voltage levelcontroller 400. In the third example embodiment, the PMOS transistor CPof FIG. 12 a is not used. The drain of the NMOS transistor CN isconnected to the drains of the PMOS transistors P₀, . . . P_(m). Thevoltage Voltage_Level is outputted from the drain of the NMOS transistorCN. The explanation of the other operation is omitted because it is thesame as that of the first example embodiment. Similarly, this embodimentcomprises an output voltage characteristic parameter controller thatcontrols the output signal voltage by activating a number of registersin the register array 551 via a register command processor 552.

FIG. 13 is a structural diagram showing an embodiment of the registercommand processor included in the register controller. The registercommand processor decodes a chip enable signal CEB, a write enablesignal WEB and an output enable signal OEB, and then outputs a commandsignal CMD_n for starting a program mode.

It is noted that in the foregoing description, the use of differentreference numbers in the figures and in the text to refer to similarstructures is not intended to imply that the structures are necessarilydistinct. For example, the register command processor, which is referredto as 512, 542 and 552, may be configured as a single structureconnected to all or some of the registers.

FIGS. 14 a and 14 b are timing diagrams showing the operation of theregister command processor according to an embodiment of the presentinvention. The operation of the register command processor of FIG. 13 isexplained referring to FIG. 14 a.

If the write enable signal WEB and the chip enable signal CEB areactivated to “low” levels, toggling of the output enable signal OEB isprovided to a clock input of a D flip-flop. Since there are n Dflip-flops, if the output enable signal OEB toggles n-times, an outputhaving a “high” level in a NOR gate is outputted from the n^(th)flip-flop, and then the control signal CMD_n becomes activated. However,while the output signal CMD_n is activated, if the output enable signalOEB becomes “high”, then all the D flip-flops become reset. As a result,the output signal CMD_n becomes “low”. That is, the output signal CMD_nis activated at a n^(th) falling edge of the output enable signal OEB,and inactivated when the output enable signal OEB rises to a high level.

FIG. 15 is a structural diagram showing the D flip-flop used in theprogram command processor FIG. 13. In general, a D flip-flop is acircuit for sampling and outputting a signal provided to an inputterminal at an edge of a clock signal. The circuit samples an inputsignal d at the falling edge of the clock CP. The switch S1 of themaster unit 61 is opened, and stores the input signal d in a latch whenthe clock is at a “high” level. Here, since a switch S2 of a slave unit62 is closed, the input signal d is not transmitted into a latch of theslave unit 62. If the clock CP is transited to a “low” level, the switchS1 of the master unit 61 is closed, and the switch S2 of the slave unit62 is opened. As a result, data stored in the latch of the master unit61 is stored in the latch of the slave unit 62, and the signal stored inthe latch of the slave unit 62 is continuously outputted to a nextfalling edge of the clock.

FIG. 16 is a structural diagram showing the register included in theregister array according to the present invention. The registercomprises a first amplifier 71, an input unit 72, a storage unit 73 anda second amplifier 74.

The first amplifier 71 comprises PMOS transistors P1, P2 and P3. ThePMOS transistor P1 has a gate to receive a first control signal ENP, anda source connected to a positive power source VCC. The PMOS transistorP2 has a gate connected to a first node, a source connected to a drainof the PMOS transistor P1, and a drain connected to a second node. ThePMOS transistor P3 has a gate connected to the second node, a sourceconnected to the drain of the PMOS transistor P1, and a drain connectedto the first node.

The second amplifier 74 comprises NMOS transistors N3, N4 and N5. TheNMOS transistor N3 has a gate connected to a first node, and a drainconnected to a second node. The NMOS transistor N4 has a gate connectedto the second node, and a drain connected to the first node. The NMOStransistor N5 has a gate to receive a second control signal ENN, a drainconnected to a source of the NMOS transistor N3 and a source of the NMOStransistor N4, and a source connected to ground VSS.

The input unit 72 comprises NMOS transistors N1 and N2. The NMOStransistor N1 has a gate to receive a third control signal ENW, a sourceto receive a data signal RESET(AnB), and a drain connected to the firstnode. The NMOS transistor N2 has a gate to receive the third controlsignal ENW, a source to receive a data signal SET(An), and a drainconnected to the second node.

The storage unit 73 comprises ferroelectric capacitors FC1, FC2, FC3 andFC4. The ferroelectric capacitor FC1 is connected between a fourthcontrol signal CPL and the first node. The ferroelectric capacitor FC2is connected between the fourth control signal CPL and the second node.The ferroelectric capacitor FC3 is connected between the first node andground VSS. The ferroelectric capacitor FC4 is connected between thesecond node and ground VSS.

When the control signal ENP is “low” and the control signal ENN is“high”, the first amplifier 71 and the second amplifier 74 fix thesesignals, respectively, at VCC and VSS. When the control signal ENP is“high” and the control signal ENN is “low”, the register is disconnectedfrom the power source, and does not operate.

When the control signal ENW is “high”, the input unit 72 provides datasignals SET and RESET, respectively, to the second node and the firstnode. When the control signal ENW is “low”, the first node and thesecond node are disconnected from the data signals SET and RESET.

The storage unit 73 stores data signals provided to the first node andthe second node in the ferroelectric capacitors FC1, FC2, FC3 and FC4 byregulating the control signal CPL.

The output signal RE_m is outputted from the second node. The operationof the register is explained hereinafter.

FIG. 17 a is a timing diagram showing the process of storing new datainto the register when the program command signal CMD_n is activated. Ifthe program command signal CMD_n is activated, the register commandprocessor 520 is inactivated until the program process is finished. As aresult, new data is not inputted into the register while the writingoperation is performed in the register.

In t1, the program command signal CMD_n is activated. In t2, if a datasignal DQ_n provided from the data I/O pad transits from “high” to“low”, the control signal ENW is activated and the data signals SET andRESET are provided, respectively, to the second node and the first node.The DQ_n signal is used with the CMD_n signal to generate a pulse signal(see FIG. 18). If the signal CPL becomes “high”, signals are stored inthe ferroelectric capacitors FC1 through FC4 according to the voltagesof the first node and the second node. For example, when the first nodeis “low”, and the second node is “high”, charges are stored in theferroelectric capacitors FC1 and FC4.

In t3, if the control signal ENW is “low”, the data signals SET andRESET are separated from the first node and the second node. Thevoltages of the first node and the second node are amplified by thefirst amplifier 71 and the second amplifier 74, and maintained. If thecontrol signal CPL becomes “low”, charges are re-distributed between theferroelectric capacitors FC1 and FC3, and between the ferroelectriccapacitors FC2 and FC4. Here, the voltages of the first node and thesecond node vary also. The voltage of the second node becomes higherthan that of the first node. The ferroelectric capacitors FC1 throughFC4 maintain the stored charges even when the power source is turnedoff. In t4, if the signals DQ_n becomes “high”, the program mode isfinished.

FIG. 17 b is a timing diagram showing the process of reading a signalstored in the register when the power source is initially provided tothe memory device.

In t1, if the power source reaches a stable level, a power-up detectionsignal PUP becomes “high”. If the control signal CPL is transited to a“high” level by using the signal PUP, the charges stored in theferroelectric capacitors FC1 and FC2 of FIG. 16 generate voltagedifferences in the first node and the second node.

In t2, if the sufficient voltage difference is generated, the controlsignals ENN and ENP are activated, respectively, to “high” and “low”. Asa result, the data of the first node and the second node are amplified.

After the amplification of the data is completed, the control signal CPLtransits to “low” in t3. As a result, the “high” data destroyed duringt1 is restored. Here, the control signal ENW is inactivated to “low”,and the data signals SET and RESET are not provided to the second nodeand the first node.

FIG. 18 is a circuit diagram showing the register for outputting thecontrol signals ENW and CPL. The control signal PUP is used to read datastored in the register after the initial reset, and then to restore theread data. After the program command signal CMD_n is activated, if thesignal DQ_n transits from “high” to “low”, the control signals ENW andCPL having a pulse width corresponding to the delay time of the delaycircuit are generated (see FIG. 17 a).

As discussed earlier, in the memory device of the present invention, itis unnecessary to change a mask for final production because thecharacteristic parameters of the memory device can be controlled in apackage. As a result, cost and time required to develop a memory devicecan be remarkably improved.

While the invention is susceptible to various modifications andalternative forms, specific embodiments have been shown by way ofexample in the drawings and described in detail herein. However, itshould be understood that the invention is not limited to the particularforms disclosed. Rather, the invention covers all modifications,equivalents, and alternatives falling within the spirit and scope of theinvention as defined in the appended claims.

1. A memory device capable of controlling a characteristic parameter,comprising: a first register controller comprising a nonvolatile memoryunit configured to store data; a first current controller configured tooutput an amount of current that is controlled according to a signaloutputted from the first register controller; a signal processorconfigured to receive an external signal, and change and output avoltage level of the received external signal according to the amount ofcurrent outputted from the first current controller, wherein the signalprocessor comprises a voltage fixing means for receiving a controlsignal and for fixing a signal outputted from the signal processor at apredetermined voltage level regardless of the external signal when thecontrol signal is inactivated; and a buffer configured to receive asignal outputted from the signal processor.
 2. The memory deviceaccording to claim 1, wherein the external signal received by the signalprocessor is one of an address signal, a data signal and a controlsignal.
 3. The memory device according to claim 1, wherein the signalprocessor comprises: a second register controller comprising anonvolatile memory unit configured to store data; a second currentcontroller configured to control an amount of current that is controlledaccording to a signal outputted from the second register controller; acapacitor connected between an output terminal of the second currentcontroller and ground; and a delay controller configured to delay theexternal signal for a predetermined time according to the amount ofcurrent outputted from the second current controller and a capacitanceof the capacitor, and output the delayed signal.
 4. A memory devicecapable of controlling a characteristic parameter, comprising: aregister controller comprising a nonvolatile memory unit and configuredto output a plurality of signals; a current controller configured tocontrol an amount of current outputted according to the plurality ofsignals outputted from the register controller; and a delay controllerconfigured to delay an externally inputted signal for a predeterminedtime according to the amount of current outputted from the currentcontroller and a capacitance of a capacitor connected between an outputterminal and a ground, and output the delayed signal.
 5. A memory devicecapable of controlling a characteristic parameter, comprising: aregister controller comprising a nonvolatile memory unit and configuredto output a plurality of signals; a current controller configured tocontrol an amount of current outputted according to the plurality ofsignals outputted from the register controller; a current fixercomprising a first end and a second end and configured to fix the anamount of current flowing through both ends; and a voltage generatorconnected between the current controller and the current fixer, andconfigured to output a predetermined voltage according to an externallyinputted control signal, the amount of current outputted from thecurrent controller, and the amount of current flowing through thecurrent fixer.
 6. The memory device according to claim 4, wherein thecurrent controller comprises a plurality of PMOS transistors eachcomprising a gate, a drain and a source, wherein for each of theplurality of PMOS transistors the gate is connected to receive one ofthe plurality of signals outputted from the register controller, thesource is connected to a common positive power source, and the drain isconnected to a common current output.
 7. The memory device according toclaim 5, wherein the current controller comprises a plurality of PMOStransistors each comprising a gate, a drain and a source, wherein foreach of the plurality of PMOS transistors the gate is connected toreceive one of the plurality of signals outputted from the registercontroller, the source is connected to a common positive power source,and the drain is connected to a common current output.